PET (Positron Emission Tomography) is a diagnostic imaging procedure that detects disease. PET scans produce images that can help to identify many forms of cancer, damaged heart tissue, and brain diseases, such as Alzheimer’s, Parkinson’s, and epilepsy. A PET scan is very different from an ultrasound, X-ray, MRI, or CT. These tests detect changes in the body structure or anatomy; whereas, a PET scan gives information about the body’s physiology. A PET scan detects abnormalities in cellular activity and can, in many cases, identify diseases earlier and more specifically than other imaging techniques.
A PET scan begins with the injection of a radiopharmaceutical (FDG), which is a radioactive sugar. This travels through the body, and by way of our body's metabolism, is collected in our organs and tissues. Once the substance has been given time to circulate, the patient will lie flat on a bed that moves through the PET scanner. The radiation that is emitted from the radiotracer is detected by the scanner and processed by a computer to generate images of the body.
PET is used to diagnose & stage various cancers. It is also useful to determine the effectiveness of cancer therapy. Cancer cells divide more rapidly than normal cells, and, in order to do so, they need more energy. The radioactive sugar (FDG) that is administered to the patient will be utilized more rapidly by the cancer cells. This increase in glucose metabolism will be detected by the PET scanner. PET is used most often for cancers of the lung, head, neck, colon, rectum, esophagus, lymphatic system, skin, breast, thyroid, cervix, pancreas, and brain.
PET scans of the heart can be used to determine blood flow to the heart muscle and help evaluate coronary artery disease. PET scans of the heart can differentiate living muscle from damaged muscle by looking at the blood flow. A PET scan identifies damaged or dead heart tissue by the lack of blood flow to that area. This information is important for patients who have had a previous myocardial infarction (heart attack) and are being considered for angioplasty or bypass surgery.
PET scans of the brain are used to diagnose Alzheimer’s, Parkinson’s, epilepsy, and other neurological conditions. The PET scan demonstrates abnormal areas of brain metabolism. Until recently, autopsy has been considered the only definitive test for Alzheimer’s disease. Studies now indicate that PET can accurately diagnose this disease. When comparing a normal brain to one affected by Alzheimer’s, there is a distinct imaging pattern demonstrated utilizing PET techniques. Early diagnosis can provide the patient access to therapies, which are more effective earlier in the disease process. PET is also useful in differentiating Alzheimer’s from other forms of brain dementia.
PET is one of the most accurate methods available to localize areas of the brain causing epileptic seizures and to determine if surgery is a viable treatment option.
You should follow a high protein, low carbohydrate diet for 24 hours prior to your test. High Protein Foods: eggs any style, bacon, sausage, steak, chicken, salmon (no breaded meat), vegetables, tossed salad with a vinaigrette type dressing. Foods to avoid: refined sugar, all fruits, all fruit juices, all sodas, all breads, cereal, chips, corn, granola, muffins, oatmeal, pasta, peas, potatoes, pretzels, rice, rice cakes, tortillas, yams…etc.
Nothing to eat or drink (except water) after MIDNIGHT the day of your scan (including no chewing gum, breath mints, cough drops or anything that may contain sugar). If your scan is scheduled for the afternoon, you may have a light breakfast at least six hours prior to your scan, as long as it follows the high protein diet. You will have your blood sugar tested upon arrival and failure to follow the preparation could cause your blood sugar to be too high to be able to do the test.
Please drink ONLY WATER up until the time of your test. Anything other than water may affect your test. Do not perform any physical activity for at least 24 hours prior to your scan.
If you need any medication for pain or anxiety, please bring it with you.
You may take your regularly scheduled medications prior to arriving for your scan, if they can be tolerated on an empty stomach.
If you are diabetic, take your oral medication as usual the morning of the exam. You should NOT take any insulin within 6 hours of the exam. Generally, your blood sugar level should be 100-200 mg/dL before your PET scan. If your blood sugar does not run within this range on a daily basis, please inform the PET center staff prior to your appointment. Your PET scan results will be sent to your referring physician within approximately 24 business hours. Please contact your physician to discuss your PET scan results.
Please arrive at the facility at your scheduled appointment time. The appointment time that you are given has time built in for paperwork; therefore, you do not need to arrive early. Because we special order our doses custom to each patient and the time of their appointment, arriving early will not assist in being scanned any sooner. Plan to spend 1.5 to 2 hours at our facility.
Wear loose fitting clothing with no metal buttons, zippers, snaps, etc. The center tends to be cold, so dress warm.
Upon arriving at the PET center, the patient will receive an IV and a small amount of radioactive glucose will be given. After the injection, the patient will wait an hour to allow the glucose to circulate throughout the body. Once the hour is over, the patient will lay down on the bed/table and the images will begin. The patient will be laying flat on his/her back with the arms above the head. First, there will be a short CAT scan, in which IV iodine contrast will be given. Then, immediately after the CT scan is complete, the PET scan will begin. The PET portion of the test can take anywhere from 20 minutes to an hour, depending on the patient weight, height, and specific exam.
PET results are interpreted by a radiologist who is a physician trained to supervise and interpret radiological examinations. The radiologist will analyze all the images taken during your exam and send a signed report to the ordering physician this will take 24 to 48 hours, additional copies can be sent upon request to primary care physicians or specialists. The ordering physician or your primary care physician will go over the results with you.